Effects Of Bioceramic Materials On The Expression Of BFGF,Nrf2 In The Blood Supply Reconstruction Of Young Permanent Teeth

ObjectivesThe models of periapical periodontitis and dental pulp revascularization in SD rats were established and compared with bFGF,Nrf2 and TNF-?in peri-apical periodontitis of young permanent teeth in SD rats.The effect of VEGF expression provides experimental basis for the treatment of periapical periodontitis in young permanent teeth.MethodsThis lab is divided into two parts.Part one:Establishment of periapical periodontitis model of maxillary first molar in SD rats.Twelve newly weaned 3-week-old SD rats were randomly selected.Six maxillary first molars were used as the experimental group and the other six as the control group.In the experimental group,endotoxins were applied to the medullary cavity and the pulp cavity was opened in the oral cavity for 1week.6 rats in the control group were killed immediately,and the animals in the experimental group were killed 1 week after exposure to the medullary cavity,and the maxillary tissue was isolated from the maxilla.The rats in the experimental group were killed at 1 week after exposure to the medullary cavity.Imaging,histology,immunohistochemical staining and SYBR Green?Real Time PCR were performed.The animals in the experimental group and the control group were killed after neck removal,the maxillary bones were separated and fixed for 24 hours.Micro-CT imaging system was used to scan the specimens required for the experiment one by one and three-dimensional reconstruction.After scanning,the specimens were made for HE staining and immunohistochemical staining to detect the expression of bFGF,Nrf2.Total RNA,Real Time PCR was extracted from periapical and endodontic tissues to detect the expression of inflammatory factor TNF-?,and the results were analyzed statistically.Part two:the establishment of the model of blood supply reconstruction of the first molar of maxillary teeth in SD rats.Thirty 3-week-old SD rats were randomly selected as experimental group with 48 maxillary first molars as experimental group and 6 with 12teeth as control group.24 rats were randomly divided into four groups.The first part of the experiment resulted in periapical periodontitis in rats in the experimental group.The root canals of the experimental group were removed with 6 and 8 K files,and the pulp was removed.The root canal was washed alternately with Naclo rinse solution and normal saline.After sterilizing the paper tip,the root canal was wiped dry,and the K file was placed over the apical foramen.The periapical tissue was stimulated to bleed to the level of root canal orifice.After the formation of blood clot,the whole hemagglutination surface was covered with Ca?OH?₂,MTA,MTA-?Angules and Iroot-BP Plus respectively.Glass ionomer cement?GIC?was used for crown filling,and then to detect the presence of suspension along the edge of the filling body,and to confirm the stability of the filling material,once the filling material fell off during the experiment.The above experimental steps of blood supply reconstruction were carried out again.Keep aseptic operation as far as possible and control the operation time.Four weeks after operation,the animals in the experimental group and the control group were killed to separate the maxillary bone.The next step of histology,imaging analysis,immunohistochemical staining and Real Time PCR detection were performed with the first part of the experiment.The results of the experiment were statistically analyzed.Results1 Establishment of periapical periodontitis model of maxillary first molar in mice.Micro-CT showed that periapical bone destruction could be observed in the periapical periodontitis group one week after operation,and the apical shadow was much larger than that in the control group.The results of histologic HE staining showed that the root canal was filled with necrotic substance and infiltrated by macrophages,neutrophils,lymphocytes and other chronic inflammatory cells.The expression of TNF-?mRNA was significantly higher in the root canal than that in the control group?P<0.05?.2Establishment of reconstructive model of pulp blood supply of maxillary first molars in mice.At 4 weeks after operation,the crowns in the pulp revascularization group were intact and there was no fracture or looseness of the teeth.Micro-CT showed that in the pulp revascularization group,high-density filling images could be seen in the crowns of the maxillary first molars,which closed the root canal orifice and narrowed the root canal cavity,and the root canal cavity was narrowed in the pulp revascularization group.Tube wall thickened,root tip expanded,new hard tissue formed,apical foramen narrowed.Histological analysis showed that the vascularized neonate tissue grew into the lumen,bone-like and cartilage-like tissue deposited at the root tip,and the expression of VEGF was significantly higher than that of the control group?P<0.05?.In Iroot-BP Plus group,the wall of root canal was thickened,the new hard tissue was the most obvious,and the development effect of tooth root was the best.The effect of Ca?OH?₂ group was the worst.In histologic data analysis,the expression of VEGF in Iroot-BP Plus group was the highest,followed by MTA and MTA-Angules group,Ca?OH?₂ was the lowest.Conclusions1 The experimental results showed that the periapical periodontitis model of the maxillary first molar in SD rats was successfully established and the periapical lesions were observed.2 The results showed that,Ca?OH?₂,MTA,MTA-?Angules and Iroot-BP Plus could induce different degrees of new tissue formation and apical development in the process of dental pulp revascularization.In this study,we successfully established the model of blood supply reconstruction of the first maxillary molars in SD rats after pulp removal.Figure38;Table6;Reference90...